"If Bob Corker has any honor, any decency, he should resign immediately," said Bannon, who after leaving the White House returned to his post atop the far-right website Breitbart News.

During a Sunday-morning tweetstorm, Trump criticized Corker and claimed the senator had unsuccessfully sought his endorsement for reelection in 2018. Corker disputed that assertion, saying that Trump had offered his endorsement just last week but that Corker had already decided he would not seek reelection in 2018.

Corker then criticized Trump's social-media ramblings and said the White House was becoming an "adult day-care center," suggesting West Wing aides and Cabinet officials were in an ongoing struggle to contain Trump's impulsive behavior.

Corker, who chairs the Senate Foreign Relations Committee, has ramped up his criticism of Trump since May, when he expressed his dismay at Trump for revealing sensitive information to Russian diplomats during an Oval Office meeting. Corker said at the time that the White House was in a "downward spiral."

The senator admonished Trump again in August for the president's response to a white-nationalist rally in Charlottesville, Virginia, that turned deadly, and more recently he decried the way Trump had publicly undermined Secretary of State Rex Tillerson.

Corker took his criticism of Trump a step further in an interview with The New York Times published Sunday night, in which he voiced concern about Trump's ability to lead and suggested Trump's rhetoric could put the US "on the path to World War III."

Bannon and his allies have signaled that they will back a slew of primary challengers to establishment-aligned Republican senators next year. Among those is Rep. Marsha Blackburn, who has announced she will run for the seat that will be vacated by Corker.